Allocating processing resources for multiple instances of a software component

ABSTRACT

Methods and corresponding systems for allocating processing resources for a number of instances (N) of a software component include determining an average processing cost (μ) and a variance (σ 2 ) for the software component. Then a processing cost for the software component is estimated as a function of N, the average processing cost (μ), and the variance (σ 2 ), and processing resources are allocated in response to the estimated processing cost. The software component can be partitioned into a number of blocks (L), wherein the L blocks include a required block and one or more optional blocks. In some embodiments in response to a total estimated processing cost exceeding an available processing value, selected optional blocks can be disabled to reduce the total estimated processing cost to a value equal to or less than the available processing value. The optional blocks can be prioritized and disabled in order of priority.

FIELD OF THE INVENTION

This invention relates in general to allocating data processingresources in a data processing system, and more specifically totechniques and apparatus for allocating data processing resources for anumber of instances of a software component using statistical analysis.

BACKGROUND OF THE INVENTION

In a voice or video communication system, data processing resources,such as processor cycles or processing time, is frequently allocatedamong multiple instances of a software component, where such instancesare created to handle multiple communication channels. For example, avoice communications system such as a telephone system can includemultiple instances of a software component that cancels echoes insignals transmitted over various channels. One method of allocatingprocessing resources to a channel is to compute the worst-caserequirement for each channel, and allocate the worst case number ofcycles to each channel.

In many voice or video communications systems, these multiple instancesof software components are of the type that can tolerate certain lossesof data, or a certain amount of unprocessed data, without significantlyaffecting a quality of service level. For example, if the echoes in oneframe of voice data were not precisely canceled, the user will probablynot notice, and parameters that set the quality of service will probablynot be violated.

Since data processing resources, such as processing cycles, are likelyan expensive addition to the design of data communication equipment, itis desirable to maximize the use of the available data processingresources, and to provide a maximum level of data processing servicewith a minimum level of data processing resources.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures, wherein like reference numerals refer toidentical or functionally similar elements throughout the separate viewsand which together with the detailed description below are incorporatedin and form part of the specification, serve to further illustratevarious embodiments and to explain various principles and advantages,all in accordance with the present invention.

FIG. 1 depicts, in a simplified and representative form, a high-leveldiagram of a communications network for connecting communicationtransceivers in accordance with one or more embodiments;

FIG. 2 shows a model of a processing unit coupled to a memory thatstores data associated with a plurality of instances of a softwarecomponent in accordance with one or more embodiments;

FIG. 3 is a high-level flowchart of processes executed by a processingunit for allocating processing resources in accordance with one or moreembodiments; and

FIG. 4 shows a high-level functional block diagram of a resourceallocation unit that may be used to allocate processing resources inconjunction with the systems of FIGS. 1 and 2 in accordance with one ormore embodiments.

DETAILED DESCRIPTION

In overview, the present disclosure concerns allocating processingresources of a data processing unit in accordance with statisticallybased estimated processing requirements. More particularly variousinventive concepts and principles embodied in methods and apparatus maybe used for scalably controlling and allocating resources of a dataprocessing unit among multiple instances of a software component inresponse to statistical characterizations of the software component.

While the processing resource allocation system of particular interestmay vary widely, one embodiment may advantageously be used in acommunication system for processing data in multiple channels, whereinsuch processing can include, for example, echo cancellation, filtering,data processing enhancement, noise reduction, automatic level control,video processing, and the like. However, the inventive concepts andprinciples taught herein may be advantageously applied to other dataprocessing systems wherein a processing unit allocates processingresources to multiple instances of software that are executing anapplication that can tolerate sporadic degradation of data withoutsignificantly affecting quality of service (QoS). Such systems canexploit the statistical properties of data traffic to achieve astatistical multiplexing processing resource gain, which increasesaverage system utilization to increase channel or function density onembedded systems.

The instant disclosure is provided to further explain, in an enablingfashion, the best modes, at the time of the application, of making andusing various embodiments in accordance with the present invention. Thedisclosure is further offered to enhance an understanding andappreciation for the inventive principles and advantages thereof, ratherthan to limit the invention in any manner. The invention is definedsolely by the appended claims, including any amendments made during thependency of this application, and all equivalents of those claims asissued.

It is further understood that the use of relational terms, if any, suchas first and second, top and bottom, and the like, are used solely todistinguish one entity or action from another without necessarilyrequiring or implying any actual such relationship or order between suchentities or actions.

Much of the inventive functionality and many of the inventive principlesare best implemented with, or in, integrated circuits (ICs), includingpossibly application specific ICs, or ICs with integrated processingcontrolled by embedded software or firmware. It is expected that one ofordinary skill—notwithstanding possibly significant effort and manydesign choices motivated by, for example, available time, currenttechnology, and economic considerations—when guided by the concepts andprinciples disclosed herein will be readily capable of generating suchsoftware instructions and programs and ICs with minimal experimentation.Therefore, in the interest of brevity and minimization of any risk ofobscuring the principles and concepts according to the presentinvention, further discussion of such software and ICs, if any, will belimited to the essentials with respect to the principles and concepts ofthe various embodiments.

Referring now to FIG. 1, a high-level diagram of a communication networkfor connecting communication transceivers in accordance with one or moreembodiments will be briefly discussed and described. In FIG. 1, system100 includes communication gateway 102 and communication transceivers104 and 106. In one exemplary embodiment, communication gateway 102 is acentral office in a communication network, such as a telephone system,wherein communication gateway 102 processes data for multiplecommunication transceivers, such as 104 and 106. Communicationtransceivers 104 and 106 can be terminal equipment, such as a telephoneor videophone, or the like. Communication transceivers 104 and 106 arecoupled to communication gateway 102 via a communication channel 108,which channel can be, in a typical embodiment, a two-line or four-linecopper wire or transmission line.

Communication gateway 102 uses processing unit 110 to process data orsignals received or transmitted to the multiple connected communicationtransceivers 104 through 106. When data processing unit 110 processesdata for multiple channels, an instance of a software component can becreated for each channel, as illustrated by instances of echo canceller112. An instance of a software component has instance data (i.e.,component data) stored in instance memory (i.e., component memory),which are spawned or created as new channels are needed. Each instanceof the software component is analogous to a parallel task executed in amultitasking processor system, wherein a single processor shares time orprocessor cycles (measured in terms of million instructions per second(MIPS) or million cycles per second (MCPS)) according to a schedule sothat tasks are said to be run in “parallel.”

An example of a processing task that can be performed on eachcommunication channel is echo cancellation. Echoes, which are delayedreflections of a communications signal, can appear in the communicationchannel because of impedance mismatches, or because of acousticalleakage from a telephone speaker to a telephone microphone. Thus, echocanceller software components 112 are created as needed to supportcommunication transceivers (e.g., telephones) as new calls are initiatedand channel 108 connections are added to communication gateway 102.Switch 114 schematically represents the multitasking, or thetimesharing, or the cycle sharing of the processing resources ofprocessing unit 110, wherein the processing resources are measured inMIPS, MCPS, time slices, or other similar measures of resourceallocation.

FIG. 2 shows processing unit 110 coupled to memory 200 by data bus 202and various control signals 204. Memory 202 stores data associated witha plurality of instances of a software component. For example, areas ofmemory 200 are used to store data associated with a first softwarecomponent 206 and a second software component 208, and other similarcomponents as they arise. Within the memory area for the first softwarecomponent 206 there can be further sections of memory for storing dataassociated with subparts (e.g., blocks) of the software component,wherein some blocks 210 are required and some blocks 212 and 214 areoptional.

Other areas of memory 200 can be used to store statistical data 216,including estimated processing costs 218 associated with each softwarecomponent. As will be discussed in greater detail below, softwarecomponent data 206 and 208 represents data stored in memory 200 that isused to support separate instances of a software component, such as thesoftware components for echo cancellation 112 (see FIG. 1). Statisticaldata 216 represents data stored in memory 200 that supports theallocation of processing resources of processing unit 110 in accordancewith one or more embodiments, as discussed below in greater detail. Byway of example, the statistical data 216 can include one or morestatistical parameters normally associated with statistical variables.While the balance of this disclosure will largely focus on mean oraverage and variance, the statistical parameters can include one or moreof an average or mean or other measurements of an average, e.g., medianor the like, and assessments of dispersion of the distribution of thevariables, e.g., variance, standard deviation, or other measurements ofdispersion and the like.

With reference now to FIG. 3, there is depicted a high-level flowchartof processes executed by a processing unit, such as the processing unitshown in FIGS. 1 and 2, or other similar apparatus, for allocatingprocessing resources in accordance with one or more embodiments.

Note that several blocks in FIG. 3 may be completed before beginning theiterative process of allocating processing resources for each processingperiod. For example, as will be described more completely below,“software components” may be partitioned into “required blocks” (see210) and “optional blocks” (see 212, 214) as the system for resourceallocation is designed, rather than, for example, during each data framewhile processing a voice signal.

As illustrated, process 300 begins at 302, and thereafter passes to 304,wherein the process partitions a software component into a requiredblock and one or more optional blocks. The software component can be aninstance of a software process that is created and is executed on a perchannel basis in a multichannel communication gateway. Thus, if aprocessing unit is responsible for the processing of data for tenchannels, there will typically be ten instances or copies of the same orsimilar software component data being processed in a multitaskedparallel configuration.

A block can be a part of a software component and can represent adistinct sub-function of the overall function performed by the softwarecomponent. For example, in one embodiment the software component mayhave the function of echo cancellation, while a block in the softwarecomponent may have the sub-function of filtering the audio signal, orenhancing the audio signal, or executing some other function that issmaller than the whole.

One of the blocks can be identified as a required block. The requiredblock executes the basic function of the overall software component.Without executing the required block, the function of the softwarecomponent will not be accomplished. In the example of the echocancellation software component, the required block can be the basicecho canceling software.

Other blocks in the software component can be identified as optionalblocks. Optional blocks are not required to execute at all times thatthe required block is executed to perform its function. Optional blockscan add features, or improve quality, or otherwise improve or add to thefunctioning of the software component. In the echo cancellation softwarecomponent, the optional blocks can perform filtering, filter coefficientupdates, noise suppression, noise matching, or other such functions thatenhance echo cancellation, but they are not required to execute everytime the basic echo cancellation function is executed.

As mentioned above, this process of partitioning the software componentmay be completed in a design phase conducted by the manufacturer, ratherthan being conducted in each period for which processing resources areallocated.

The next step in the process is to determine an average processing costand a variance for each of the blocks, as illustrated at 306. In oneembodiment, the blocks can be extensively profiled using representativetest signals (i.e., independent test vectors) to estimate the averageand variance of execution times. Execution times can be measured interms of MCPS, and execution time profiles can be characterized by MCPShistograms, h(m), so that the average MCPS (μ) and variance MCPS (σ²)are estimated using the first and second moments of h(m).

In the formulas below, m is a random variable representing theprocessing load per block, and the histogram h_(i)(m) is estimated as afunction of m MCPS such that Σ_(m)h_(i)(m)=1. Then the average MCPS (μ)and variance MCPS (σ²) are calculated according to the followingformulas:

$\mu_{i} = {\sum\limits_{m}{{mh}_{i}(m)}}$$\sigma_{i}^{2} = {{\sum\limits_{m}{m^{2}{h_{i}(m)}}} - \mu_{i}^{2}}$

Initial values for average processing cost and variance for each blockmay be computed by the manufacturer of the processing resourceallocation system. The initial values for average processing cost andvariance can be stored in memory, such as memory 200 shown in FIG. 2,which corresponds to lookup table 404 in the high-level functional blockdiagram of FIG. 4. Look up table 404 can be used to store statisticalconstants that have been predetermined using test vectors.

Referring briefly to FIG. 4 there is depicted a functional block diagramof the several tasks that are performed and interfaces maintained bycomposite resource allocation unit 400. The functions shown in resourceallocation unit 402 can be executed in hardware, firmware, orapplication specific integrated circuits that more specifically resemblethe processing unit 110 coupled to memory 200 in FIG. 2. The remainingblocks in resource allocation unit 402 will be explained in greaterdetail below, as such blocks can be used in the implementation of theremaining steps in FIG. 3.

Returning to FIG. 3, the next step in the process receives, as inputs,the probability of execution to completion (P₀), the available number ofcycles (M), and the number of channels (N), as depicted at 308. In FIG.4, such inputs are shown as operating system inputs 406, which are sentto resource allocation unit 402.

The probability of execution P₀ is a predefined target confidence levelreflecting the statistical likelihood that a multichannel system runningseveral independent software components will not exceed a predefinedtarget execution time or cycle budget M. P₀ is the probability that thetotal MCPS consumption in the system is smaller than or equal to M,which can be expressed as P_(o)=Prob(m≦M), where m is modeled as aNormal distribution

(Nμ_(t), Nσ_(t) ²) for the total number of blocks in all softwarecomponents. Because a failure to complete a software task within anallotted number of cycles can have an impact on the quality of service,P₀ is selected in accordance with a quality of service required by theprocessing unit. An increasing probability that a task will not becompleted decreases the quality of service.

Thus, P₀ can be expressed by the following formulas:

$\begin{matrix}{P_{o} = {{Prob}\left( {m \leq M} \right)}} \\{= {{Prob}\left( {\frac{m - {N\;\mu_{t}}}{\sqrt{N}\sigma_{t}} \leq \frac{M - {N\;\mu_{t}}}{\sqrt{N}\sigma_{t}}} \right)}} \\{= {{Prob}\left( {m^{\prime} \leq \alpha_{o}} \right)}}\end{matrix}$Where m′ is a random variable having distribution N (0, 1) and

$\alpha_{o} = \frac{M - {N\;\mu_{t}}}{\sqrt{N}\sigma_{t}}$This implies that

$P_{0} = {\frac{1}{2}\left\lbrack {1 + {{erf}\left( {\alpha_{0}\text{/}\sqrt{2}} \right)}} \right\rbrack}$where${{erf}(x)} = {\frac{2}{\sqrt{\pi}}{\int_{0}^{x}{{\mathbb{e}}^{- t^{2}}\ {{\mathbb{d}t}.}}}}$

It is important to mention that when the Normal distributionapproximation is not adequate, one may use the Tchebysheff's inequalityto estimate an upper bound on the likelihood of exceeding the availableMCPS budget as follows:

${{Prob}\left( {{\frac{m - {N\;\mu_{t}}}{\sqrt{N}\sigma_{t}}} \geq \alpha_{o}} \right)} \leq \frac{1}{\alpha_{o}^{2}}$

Note that these approximations have been experimentally validated usingstatistically independent communication channels indicating very closeagreement with theoretical predictions as the number of channels Nincreases.

The input M at 308 is the available number of cycles of the dataprocessing unit, e.g., a digital signal processor (DSP). This may bereferred to as the budgeted processing resource, which is typicallymeasured in MCPS.

The input number of channels N is the number of channels that theprocessing unit is expected to handle. This is typically the number ofinstances of the software component that are needed to handle all thedata processing. In some embodiments of an echo canceller, N can be thenumber of active phone calls.

Next, the process can perform an optional step of updating the averageprocessing cost and variance or other statistical parameters, asillustrated at 310. In one embodiment, the average processing cost andvariance for each block (required and optional) are calculated beforethe process of allocating processing resources begins. After theprocesses have been started, the average processing cost and variancecan be updated periodically by measuring the average processing cost andvariance over a recent time window, e.g., over hundreds of samples. Byupdating the average cost and variance, the calculations and the processof allocating processing resources can become more accurate for theparticular environment in which the system is used.

As shown in FIG. 4, the process of updating statistics may beimplemented within resource allocation unit 402 in an update statisticsblock 410. To update the average processing cost and variancestatistics, the process monitors the number of cycles (obtained via eachsoftware component 414) required by each block, and calculates acorresponding average and variance accordingly. The process of measuringthe number of cycles required by a block can be implemented in theoperating system.

Next, the process 300 estimates the processing cost m_(i) for each blockbased on the number of channels N, and the average processing cost μ_(i)and the standard deviation σ_(i) for each block, as depicted atflowchart block 312. In one embodiment, based on the previous equationsof α₀ and P₀, the estimated processing cost for each block m_(i) of Lnumber of blocks can be calculated according to the formula:

$\begin{matrix}{m_{i} = {\mu_{i} + {\alpha \cdot \sigma_{i}}}} & {{{{for}\mspace{14mu} i} = 0},\ldots\mspace{11mu},{L - 1}}\end{matrix}$${{where}\mspace{14mu}\alpha} = {\frac{\sqrt{2}{{erf}^{- 1}\left( {{2 \cdot P_{0}} - 1} \right)}}{\sqrt{N}}.}$

Thus, α is a statistical scaling factor that is a function of a selectedprobability of completion P₀ of the blocks, and the number of channelsN. This makes the estimate of the processing cost a function of N, theaverage processing cost, and the variance for each block.

After estimating the processing cost for each block, the processestimates the total processing cost for all blocks in all N channels, asillustrated at 314. This can be implemented by summing all of theestimated processing cost m_(i) for each of the L blocks, andmultiplying by N, which is the number of channels. This step can beimplemented in processing unit 110 (see FIG. 2) by the budget allocationunit 408 (see FIG. 4).

Once the total processing cost is estimated, the process determineswhether the estimated total processing cost exceeds the availableprocessing resources, as depicted in 316. If the total estimatedprocessing cost does not exceed the available processing resources, theprocess passes to 318, wherein the processing resources are allocated.Since there will not be a shortage of processing resources, there are nodifficult decisions concerning how to cut back the allocations to thevarious blocks or components.

However, if, at 316, the total estimated processing cost exceeds theavailable processing resources, the process passes to 322, wherein theoptional blocks are prioritized. The prioritization can be implementedin priority control unit 412 in FIG. 4. In some embodiments, blockprioritization can occur based on several factors or considerations. Inone embodiment, the optional blocks can be prioritized according totheir impact on the quality of service. For example, if voice data isbeing processed, some optional blocks may contribute greatly to theperceived quality of the voice, while other optional blocks are hardlynoticed if they were not executed. In other embodiments, the optionalblocks may be prioritized according to the number of cycles needed toexecute the optional block. In some embodiments, some blocks caninitially have a higher priority, and then be changed to a lowerpriority as the process of allocating resources proceeds. For example,updating the coefficients of an adaptive filter can initially have ahigh priority, and then be changed to a lower priority as the filterconverges. Additionally, the priorities of optional blocks may beperiodically changed or evaluated based on feedback 414 from theoptional blocks, wherein such feedback may include an indication ofwhether or not the execution of the block was completed with previouslyallocated resources.

Once the optional blocks are prioritized, the process disables selectedlowest priority optional blocks, as depicted at 324. In one embodiment,the lowest priority block can be disabled in the software component forone or several of the N channels.

After disabling selected low priority optional blocks, the processcalculates a new estimate of the total processing cost, as illustratedat 326. Then, the new total estimated processing cost is compared to theavailable processing resources, and the process once again determineswhether or not the new estimated processing cost exceeds the availableprocessing resources, as depicted at 328.

If the new estimated total processing cost does not exceed theprocessing resources available, the process proceeds to 318 to allocatethe processing resources according to the selection of enabled anddisabled optional blocks. In one embodiment, the allocation of resourcescan take the form of control signals that enable and disable theexecution of selected optional blocks of the N software components. InFIG. 4, this allocation is shown as resource allocation 416, which isoutput from MIPS/MCPS budget allocation unit 408.

If the new total estimated cost exceeds the available processingresources, the process disables additional selected low priorityoptional blocks, as illustrated at 330. Then the process iterativelyreturns to block 326 to calculate a new estimated total processing cost,and to determine if the new total falls within the available processingresources.

In some embodiments, the iterative process of selecting and disablinglow priority optional blocks (324 and 330) may be implemented wherein asingle optional block for a single software component instance isdisabled before estimating a new estimated total cost and comparing itto the available processing resources. In other words, the process mayproceed by disabling one optional block in one software componentinstance at a time. In alternative embodiments, groups of selected lowpriority optional blocks may be disabled in one or more selectedsoftware components before calculating and comparing a new estimate ofthe total cost.

The above described functions and structures can be implemented in oneor more integrated circuits. For example, many or all of the functionscan be implemented in the signal and data processing circuitry that issuggested by the block diagrams shown in FIGS. 1, 2, and 4. Furthermore,a similar method and structure can be used for allocating processingresources of multiple instances of more that one type of softwarecomponent.

The processes, apparatus, and systems, discussed above, and theinventive principles thereof are intended to produce an improved andmore efficient allocation of data processing resources. By selecting theappropriate probability P₀ that a software component will be completed,the processing resource allocation can be performed efficiently, withgains in processing density achieved by sacrificing an appropriateincremental level of quality that results when all the blocks of eachsoftware component cannot be completely executed. Additionalefficiencies are gained when a software component is subdivided intoprioritized optional blocks that can be selectively disabled to meet theavailable or budgeted processing resources. Selectively disablingoptional blocks can gracefully degrade the system in a controlled andpredictable fashion. If the available MIPS/MCPS and the number ofchannels are large enough, then using statistical provisioning canprovide a multiplexing gain per channel proportional to the differencebetween the total peak and average MIPS/MCPS.

While the embodiments discussed above primarily relate to allocatingprocessor cycles to an echo cancellation software component, the systemfor allocating processor resources to multiple instances of a softwarecomponent can be used in other data processing applications, such assignal processing and filtering, video processing, graphics processing,character or object recognition, or other similar processes that areexecuted in parallel, and that can tolerate sporadic errors withoutsignificantly affecting the quality of service. If such processes can besubdivided into required and optional blocks, wherein optional blocksmay be selectively disabled, additional statistical processing gain canbe achieved. While this description and disclosure has focused on theaverage or mean and variance parameters, it will be appreciated thatother statistical parameters corresponding to various averages, e.g.,median or the like, and distribution dispersion, e.g., standarddeviation or the like can also be used for advantageously allocatingprocessor resources in accordance with corresponding statisticalmeasurements.

This disclosure is intended to explain how to fashion and use variousembodiments in accordance with the invention, rather than to limit thetrue, intended, and fair scope and spirit thereof. The foregoingdescription is not intended to be exhaustive or to limit the inventionto the precise form disclosed. Modifications or variations are possiblein light of the above teachings. The embodiment(s) were chosen anddescribed to provide the best illustration of the principles of theinvention and its practical application, and to enable one of ordinaryskill in the art to utilize the invention in various embodiments andwith various modifications as are suited to the particular usecontemplated. All such modifications and variations are within the scopeof the invention as determined by the appended claims, as may be amendedduring the pendency of this application for patent, and all equivalentsthereof, when interpreted in accordance with the breadth to which theyare fairly, legally, and equitably entitled.

1. A method for allocating processing resources for a number ofinstances (N) of a software component and a probability of completion(Po) comprising: in a processing unit; determining an average processingcost (μ) and a variance (σ²) for the software component; estimating aprocessing cost for the software component as a function of N, theprobability of completion (Po), the average processing cost (μ), and thevariance (σ²); and allocating processing resources in response to theprocessing cost.
 2. The method for allocating processing resourcesaccording to claim 1 wherein the estimating a processing cost for thesoftware component, and the allocating processing resources, comprises:partitioning the software component into a number of blocks (L blocks),wherein the L blocks include at least one required block and one or moreoptional blocks; determining an average processing cost (μ_(i)) and avariance (σ_(i) ²) for each of the L blocks; estimating an estimatedprocessing cost (m_(i)) for each of the L blocks as a function of N, andthe respective average processing cost (μ_(i)) and variance (σ_(i) ²) ofthe L blocks; and allocating processing resources in response to theestimated processing cost m_(i) for each of the L blocks.
 3. The methodfor allocating processing resources according to claim 2 wherein theestimating an estimated processing cost (m_(i)) for each of the L blockscomprises: computing a scaling factor (α) that is a function of N andthe probability of completion (P₀) of the L blocks; and estimating anestimated processing cost (m_(i)) for each of the L blocks as a functionof N, the probability of completion (P₀), and the respective averageprocessing cost (μ_(i)) and variance (σ_(i) ²) for each of the L blocksaccording to the formula m_(i)=μ_(i)+α·σ_(i).
 4. The method forallocating processing resources according to claim 3 further comprisingselecting the probability of completion (P₀) to achieve a quality ofservice (QoS) level.
 5. The method for allocating processing resourcesaccording to claim 3 wherein the computing a scaling factor (α) that isa function of N and the probability of completion (P₀) comprisescomputing the scaling factor (α) according to the formula$\alpha = {\frac{\sqrt{2}{{erf}^{- 1}\left( {{2 \cdot P_{0}} - 1} \right)}}{\sqrt{N}}.}$6. The method for allocating processing resources according to claim 2wherein the allocating processing resources comprises: adding theestimated processing cost m_(i) for each of the L blocks in each of theN software components to compute a total estimated processing cost forthe N software components; comparing the total estimated processing costto an available processing value; and in response to the total estimatedprocessing cost exceeding the available processing value, disablingselected optional blocks to reduce the total estimated processing costto a value equal to or less than the available processing value.
 7. Themethod for allocating processing resources according to claim 6 whereindisabling selected optional blocks comprises: prioritizing the optionalblocks; and disabling a selected lower priority optional block beforedisabling a selected higher priority optional block.
 8. The method forallocating processing resources according to claim 2 wherein thepartitioning the software component into a number of blocks (L blocks),wherein the L blocks include at least one required block and one or moreoptional blocks comprises partitioning an echo canceller softwarecomponent into L blocks, wherein the L blocks includes a required echocancelling block and one or more optional quality-enhancing blocks. 9.The method for allocating processing resources according to claim 2further comprising updating the average processing cost (μ_(i)) andvariance (σ_(i) ²) for one or more of the L blocks based uponmeasurements in a preceding time window.
 10. A system for allocatingprocessing resources for a number of instances (N) of a softwarecomponent and a probability of completion (Po) comprising: a data memoryfor storing data associated with the N instances of the softwarecomponent; and a processing unit coupled to the data memory, wherein theprocessing unit and the data memory are cooperatively operable forexecuting the N instances of the software component, and for: estimatingan estimated processing cost for the software component as a function ofN, the probability of completion (Po), an average processing cost (μ)and a variance (σ²) for the software component; and allocatingprocessing resources in response to the estimated processing cost. 11.The system for allocating processing resources according to claim 10wherein the software component is partitioned into a number of blocks (Lblocks), wherein the L blocks include at lest one required block and oneor more optional blocks, and wherein the processing unit and the datamemory are further cooperatively operable for: estimating a processingcost (m_(i)) for each of the L blocks as a function of N, and arespective average processing cost (μ_(i)) and a variance (σ_(i) ²) ofeach of the L blocks; and allocating processing resources in response tothe estimated processing cost m_(i) of the L blocks.
 12. The system forallocating processing resources according to claim 11 wherein theprocessing unit and the data memory are further cooperatively operablefor: computing a scaling factor (α) that is a function of N and theprobability of completion (P₀) of the L blocks; and estimating anestimated processing cost (m_(i)) for each of the L blocks as a functionof N, the probability of completion (P₀), and the respective averageprocessing cost (μ_(i)) and variance (σ_(i) ²) for each of the L blocksaccording to the formula m_(i)=μ_(i)+α·σ_(i).
 13. The system forallocating processing resources according to claim 12 wherein theprobability of completion (P₀) is selected to achieve a quality ofservice (QoS) level.
 14. The system for allocating processing resourcesaccording to claim 12 wherein the processing unit and the data memoryare further cooperatively operable for computing the scaling factor (α)according to the formula$\alpha = {\frac{\sqrt{2}{{erf}^{- 1}\left( {{2 \cdot P_{0}} - 1} \right)}}{\sqrt{N}}.}$15. The system for allocating processing resources according to claim 11wherein the processing unit and the data memory are furthercooperatively operable for: adding the estimated processing cost m_(i)for each of the L blocks in each of the N software components to computea total estimated processing cost for the N software components;comparing the total estimated processing cost to an available processingvalue; and in response to the total estimated processing cost exceedingthe available processing value, disabling selected optional blocks toreduce the total estimated processing cost to a value equal to or lessthan the available processing value.
 16. The system for allocatingprocessing resources according to claim 15 wherein the processing unitand the data memory are further cooperatively operable for: prioritizingthe optional blocks; and disabling a selected lower priority optionalblock before disabling a selected higher priority optional block. 17.The system for allocating processing resources according to claim 11wherein the software component comprises an echo cancelling softwarecomponent, and wherein the L blocks include a required echo cancellingblock and one or more optional quality-enhancing blocks.
 18. The systemfor allocating processing resources according to claim 11 wherein theprocessing unit and the data memory are further cooperatively operablefor updating the average processing cost (μ_(i)) and variance (σ_(i) ²)for one or more of the L blocks based upon measurements in a precedingtime window.
 19. A method for allocating processing resources for anumber of instances (N) of a software component and a probability ofcompletion (Po) comprising: in a processing unit; partitioning thesoftware component into a number of blocks (L blocks), wherein the Lblocks include at least one required block and one or more optionalblocks; determining an average processing cost (μ_(i)) and a variance(σ_(i) ²) for each of the L blocks; computing a scaling factor (α) thatis a function of N and the probability of completion (P₀) of the Lblocks; estimating an estimated processing cost (m_(i)) for each of theL blocks as a function of α, and the respective average processing cost(μ_(i)) and variance (σ_(i) ²) of the L blocks; and allocatingprocessing resources in response to the estimated processing cost m_(i)for each of the L blocks.
 20. The method for allocating processingresources according to claim 19 comprising: adding the estimatedprocessing cost m_(i) of each of the L blocks in each of the N softwarecomponents to compute a total estimated processing cost for the Nsoftware components; comparing the total estimated processing cost to anavailable processing value; and in response to the total estimatedprocessing cost exceeding the available processing value, disablingselected optional blocks to reduce the total estimated processing costto be equal to or less than the available processing value.